Sudden Fissure sub-table
d6
1. pit: 3d6 feet wide, 1d12x10 feet deep
2. pit, semi-bottomless, eventually fall up out of a well in dungeon in adjacent dimension
3. opens into chamber full of one million terrified bats
4. as per entry 1 plus copious poof of toxic gas
5. as per entry 4 plus surrounding floor cracks 20 feet in all directions, will collapse in 10 seconds
6. Satan (or local equivalent) rears up from below, wreathed in flame, howling with laughter